Matou Sakura

Japanese name:

間桐 桜

A student in her first year of high school, and the sister of Shinji Matō. After Shirō's father Kiritsugu died, Sakura often visited Shirō's home to help him with his daily chores. Though Shinji is from a family of sorcerers, he asserts that she has no knowledge of her family's craft or history. Sakura is outwardly shy and timid, but possesses great inner strength. She has a long standing and obvious crush on Shirō Emiya.
While Sakura plays a minor part in the Fate and Unlimited Blade Works scenarios, she plays a much larger role in the final path, Heaven's Feel. She is revealed to be Rider's true Master having used a command spell to give control to Shinji as she had no desire to fight. After the end of the previous Grail War, her grandfather implanted a piece of the Grail into Sakura in an attempt to recreate it. This led to the creation of the eighth Servant, Avenger, who tried to summon himself by controlling Sakura with an alternate persona, The Shadow. Sakura takes on the form of The Shadow at nights and kills hundreds of people in order to gain energy. She is eventually stopped when Rin attempts to kill Sakura; Sakura is revealed to be Rin's biological sister, adopted into the Matō family as their heir since Shinji lacked magical circuits. Unable to kill her sister, Rin allows Sakura to stab her instead, allowing Sakura to realize that her friends had not abandoned her and still wanted to save her, and regain control of her mind.